Cognition, Behavior, and Memory
Author: Juan Ignacio Dominguez Mateu | Email: juan.i.do@hotmail.com
Juan Ignacio Dominguez Mateu 1°, Daniel Tomsic 1°
1° Faculty of Exact and Natural Sciences, Department of Physiology, Molecular and Cellular Biology. Institute of Physiology, Molecular Biology, and Neuroscience (IFIBYNE), CONICET-University of Buenos Aires, Buenos Aires, Argentina.
2° Faculty of Exact and Natural Sciences, Department of Physiology, Molecular and Cellular Biology. Institute of Physiology, Molecular Biology, and Neuroscience (IFIBYNE), CONICET-University of Buenos Aires, Buenos Aires, Argentina.
Violinist crabs use a simple rule to categorize visual stimuli: dangerous if perceived in the dorsal region of the retina; harmless if perceived at or below the equator. The Neohelice crab also reacts to elevated moving stimuli; however, unlike the violinist crabs, it exhibits predatory behavior towards smaller crabs. Thus, depending on the elevation of movement, the same object can evoke two completely opposing behaviors, escape or pursuit. It might be assumed that, as proposed for violinist crabs, Neohelice decides how to respond to moving objects based on the retinal region with which they are detected. However, the habitats occupied by Neohelice often feature significant inclinations, causing the crab, when positioned downhill from a small object moving on the ground, to see it above itself. Consequently, according to the hypothesis of categorization by retinal position, the crab should respond by escaping and never pursuing. To test this hypothesis, we conducted experiments in a laboratory arena using a small object moved on an inclined plane. The results show that crabs can pursue and capture the object even when it moves above their eyes. Therefore, the hypothesis of the simple rule for identifying stimuli as prey or predator based on retinal position is incorrect. Crabs incorporate knowledge of substrate inclination to decide the object’s significance.